On Wednesday, the American Heart Association focused on something we're not doing that's making us sick. We're not getting enough exercise. As a result, we're more likely to get heart disease.

At a press conference in New York, heart association officials and fitness researchers said physical inactivity -- the lack of adequate exercise -- is now considered a risk factor for coronary heart disease. Inactivity joins cigarette smoking, high blood pressure and high blood cholesterol levels as significant causes of heart disease.

The association's newly approved statement on exercise notes that regular aerobic workouts improve and strengthen the body's heart-lung system, and can help control blood lipid (cholesterol) abnormalities, diabetes and obesity.

Even modest physical activity will lower a sedentary person's risk of heart disease, the artery-clogging that sets the stage for heart attacks, specialists said at the press conference. It can also lower the risk of adult-onset, or Type II, diabetes, said a study published Wednesday in the Journal of the American Medical Association.

"Too many people think of exercise as something that they have to do wearing special clothes in a special place like a gym where they sweat a lot," said Steven Blair, director of epidemiology at the Institute for Aerobics Research in Dallas.

"Probably the best rule of thumb is 30 to 60 minutes of good brisk walking or its equivalent, and do that at least every other day, three to four times a week," Blair said at the press conference Wednesday.

Gardening, yard work, house work and dancing are among other low-intensity activities that will help if done daily, the association said.

Studies suggest that 20 percent to 30 percent of American adults are sedentary enough to be at significantly increased risk

for heart disease, Blair said. That is 35 million to 50 million people, he said.

The full explanation for why exercise can lower heart disease risk is not known, said Dr. Gerald Fletcher, chairman of rehabilitation medicine at the Emory University School of Medicine in Atlanta. Among its effects are lowering high blood pressure, cutting levels of blood fats called triglycerides, and raising levels of the so-called "good cholesterol," high-density lipoproteins, he said. Part of the heart association's statement is aimed at doctors: "The physician must not neglect this responsibility to promote regular exercise and other health promotion strategies."

So are doctors getting patients into a routine of walking, biking, swimming or another activity? Local doctors who were questioned gave themselves mixed marks, but most said they could do better.

Dr. Robert Dobrow, a West Hartford cardiologist and president of the Connecticut affiliate of the American Heart Association, said doctors are generally well-informed about the benefits of exercise, but don't always share that knowledge with patients.

"I think what this statement is going to do is signal all physicians, not just cardiologists but primary care physicians of all types, to begin to get more aggressive about this," he said.

Assessing a patient's fitness level and prescribing exercise that both addresses fitness and the patient's income can be time-consuming for physicians, he said. But he said doctors have to start getting all their patients involved -- not just those recovering from heart attacks or at high risk of heart disease.

"This is going to afford an opportunity for people to buy into their own health care," he said, "and people really respond to that."

Dr. Barry L. Zaret, Robert Berliner professor of medicine and chief of the cardiology section at Yale Medical School in New Haven, agreed that putting the responsibility on the patient is essential.

"Anything you can do that provides the patient with some control over his or her fate is certainly worthwhile," he said. Zaret added that he believes his colleagues are getting better about prescribing exercise.

But Dr. Michael Butensky, a Wethersfield gastroenterologist and internist, said doctors can only do so much. Some patients don't want to exercise outside in cold weather -- and they may not have the cash for indoor exercise gear or club memberships.

"I think you can only push so hard," he said. "It's like smoking or anything."

Dr. Neil Brooks, a Vernon family practitioner, said that because moderate exercise offers benefits, doctors can get most patients into relatively simple programs -- walking, for instance -- without formal fitness testing. He added that while some doctors feel awkward about prescribing lifestyle changes, others have embraced the preventive strategy.